Retinal see through display power level determination method and apparatus

ABSTRACT

Apparatuses, methods and storage medium associated with retinal see through display are disclosed herein. In embodiments, an apparatus may comprise a retinal see through display wearable by a user; a target luminance calculator to determine a required luminance level; and a display power controller to determine a power level for the retinal see through display, based at least in part on a pupil size of the user and the determined required luminance level. Other embodiments may be described and/or claimed.

TECHNICAL FIELD

The present disclosure relates to the field of display technology. Moreparticularly, the present disclosure relates to retinal see throughdisplay power level determination method and apparatus.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Unless otherwiseindicated herein, the materials described in this section are not priorart to the claims in this application and are not admitted to be priorart by inclusion in this section.

Natural response of the human eye to a change in ambient brightnessincludes adaptation of the eye pupil diameter through action of theiris, yielding a change in retinal illumination. For optical displaysystems having an exit pupil smaller than the actual eye pupil size, themechanism provided by nature would no longer work as the retinalillumination is no longer dependent on the eye pupil diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detaileddescription in conjunction with the accompanying drawings. To facilitatethis description, like reference numerals designate like structuralelements. Embodiments are illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings.

FIG. 1 illustrates the retinal see through display power determinationtechnology of the present disclosure, according to various embodiments.

FIG. 2 illustrates the retinal see through display power determinationtechnology of the present disclosure, according to various otherembodiments.

FIG. 3 illustrates determination of display luminance, according tovarious embodiments.

FIG. 4 illustrates a component view of a wearable device having theretinal see through display power determination technology of thepresent disclosure, according to various embodiments.

FIG. 5 illustrates an example process for determining power of a retinalsee through display, according to various embodiments.

FIG. 6 illustrates a storage medium having instructions for practicingmethods described with references to FIGS. 1-3, according to variousembodiments.

DETAILED DESCRIPTION

Apparatuses, methods and storage medium associated with retinal seethrough display are disclosed herein. In embodiments, an apparatus maycomprise a body wearable by a user, a retinal see through displaydisposed in the body; a target luminance calculator disposed in the bodyto determine a required luminance level; and a display power controllercommunicatively coupled with the target light calculator and the retinalsee through display, and disposed in the body, to determine a powerlevel for the retinal see through display, based at least in part on apupil size of the user and the determined required luminance level.

In embodiments, the apparatus may further comprises sensors disposed inthe body to sense local luminance level for a local area behind avirtual image, and the target luminance calculator may becommunicatively coupled with the sensors to sense local luminance level,and determine a required luminance level based at least in part on thesensed local luminance level. In embodiments, the required luminancelevel may be determined based at least in part on the sensed localluminance level, using a required luminance model that models requiredluminance for various local luminance conditions.

In embodiments, the pupil size of the user may be estimated or detected.In estimated embodiments, the apparatus may further comprises sensorsdisposed in the body to sense ambient light level, and a pupil sizecalculator communicatively coupled with the sensors to sense ambientlight level, and disposed in the body, to estimate the pupil size basedat least in part on the sensed ambient light level. In embodiments, thepupil size may be estimated based at least in part on the sensed ambientlight level using a model that models the pupil size for various ambientlight conditions.

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof wherein like numeralsdesignate like parts throughout, and in which is shown by way ofillustration embodiments that may be practiced. It is to be understoodthat other embodiments may be utilized and structural or logical changesmay be made without departing from the scope of the present disclosure.Therefore, the following detailed description is not to be taken in alimiting sense, and the scope of embodiments is defined by the appendedclaims and their equivalents.

Aspects of the disclosure are disclosed in the accompanying description.Alternate embodiments of the present disclosure and their equivalentsmay be devised without parting from the spirit or scope of the presentdisclosure. It should be noted that like elements disclosed below areindicated by like reference numbers in the drawings.

Various operations may be described as multiple discrete actions oroperations in turn, in a manner that is most helpful in understandingthe claimed subject matter. However, the order of description should notbe construed as to imply that these operations are necessarily orderdependent. In particular, these operations may not be performed in theorder of presentation. Operations described may be performed in adifferent order than the described embodiment. Various additionaloperations may be performed and/or described operations may be omittedin additional embodiments.

For the purposes of the present disclosure, the phrase “A and/or B”means (A), (B), or (A and B). For the purposes of the presentdisclosure, the phrase “A, B, and/or C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B and C).

The description may use the phrases “in an embodiment,” or “inembodiments,” which may each refer to one or more of the same ordifferent embodiments. Furthermore, the terms “comprising,” “including,”“having,” and the like, as used with respect to embodiments of thepresent disclosure, are synonymous.

As used herein, the term “module” may refer to, be part of, or includean Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group) and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs having machine instructions (generated from assemblerinstructions or compiled from higher level language instructions), acombinational logic circuit, and/or other suitable components thatprovide the described functionality.

Referring now to FIG. 1, wherein the retinal see through display powerdetermination technology of the present disclosure, according to variousembodiments, is illustrated. As shown, in various embodiments, wearabledevice 100 may include retinal see through display (not shown in FIG. 1,see e.g., 406 in FIG. 4) having an exit pupil smaller than actual eyepupil size or within possible eye pupil size range (2-7 mm). Wearabledevice 100 may include further display power controller 114 configuredto adaptively determine an appropriate power for the retinal see throughdisplay output light beams 116 of appropriate display luminance level todisplay images to user's eye 118. In embodiments, the power level may bedetermined to be the power level that provides for the display luminancelevel to approximate or equal the required luminance level, for a pupilsize, as described more fully below.

In embodiments, to facilitate determination of the required luminancelevel, wearable device 100 may further include local light sensor 104and target light calculator 112 communicatively coupled with each other,and with display power controller 114 as shown. Local light sensor 104may be configured to sense and output local luminance level of a localarea behind a displayed virtual image (see e.g., virtual image 304displayed on the user's field of view 302 illustrated on the right handside of FIG. 3). In embodiments, local light sensor 104 may be any oneof a number of suitable light sensors known in the art configurable tobe coupled to a light pipe designed to have an acceptance angleconsistent (e.g., matching) the displayed image of view. An example ofsuch light sensors may include, but is not limited to, the Light ToDigital Converters available from AMS TAOS of Premstaetten, Austria.

In embodiments, target luminance calculator 112 may be configured todetermine the required luminance level (L_(required)), based at least inpart on the sensed local luminance level (L_(local)). In embodiments,target luminance calculator 112 may determine the required luminancelevel, using a required luminance level model 108 that models requiredluminance level for various local luminance levels.

In embodiments, L_(required) may be determined using an empirical modelrepresented by the following formula:

$\begin{matrix}{L_{required} = \sqrt{\frac{4.10^{8/8} \cdot L_{local\_ eye} \cdot p^{2}}{w}}} & (1)\end{matrix}$

where w is the virtual image solid angle in steradian,

p is an index which depends on the position of the virtual image in theuser's field of view (FOV), and

L_(local) _(_) _(eye) may be the local luminance level perceived byuser's eye 118, which may be a percentage of the sensed local luminancelevel.

For example, if wearable device 100 is an eyeglass, which lens has atint of 18% transmission, L_(local) _(_) _(eye) would be 18% of thesensed local luminance level. The determined L_(required) provides forvirtual image contrast on top of the field of view background.

In alternate embodiments, other required luminance level models may beused.

In embodiments, display power controller 114 may be configured to selecta power level for retinal see through display, such that the displayluminance level approximates or equals the required luminance level, fora pupil size.

As described earlier, the exit pupil of the retinal see through displayis smaller than the user's eye pupil, thus technology of the presentdisclosure adapt the display luminance depending on the size of the eyepupil of the user. In embodiment, the optimum power P_(opt) of theretinal see through display to provide the display luminance toapproximate or equal the required luminance may be determined using thefollowing formulas (see left hand side 310 of FIG. 3):

$\begin{matrix}{\mspace{79mu} {L = {\frac{K_{M}}{A \cdot \Omega}{\int_{380}^{780}{{P_{opt}(\lambda)}{V(\lambda)}d\; \lambda}}}}} & (2) \\{\mspace{79mu} {\Lambda \mspace{11mu} 2D\; {{\tan \left( {\theta_{h}/2} \right)} \cdot 2}D\; {\tan \left( {\theta_{v}/2} \right)}}} & (3) \\{\mspace{85mu} {\Omega = \text{?}}} & (4) \\{\text{?}\text{indicates text missing or illegible when filed}} & \;\end{matrix}$

Accordingly,

$\begin{matrix}{L = {\frac{K_{M}}{{\tan \left( {\theta_{h}/2} \right)}{\tan \left( {\theta_{v}/2} \right)}d^{2}\pi}{\int_{380}^{780}{{P_{opt}(\lambda)}{V(\lambda)}d\; \lambda}}}} & (5)\end{matrix}$

where L is the display luminance level;

-   -   P_(opt)(λ) is a spectral distribution of optical power incident        onto the eye pupil;

K_(M) is a factor which is equal to 683.002 lm/W and is the maximalphotopic spectral luminous efficacy, corresponding to lambda=555 nm;

-   -   Virtual image surface: A    -   Solid angle defined by eye pupil: Ω    -   Photopic Spectral Luminous efficiency: V(λ)    -   Eye pupil diameter: d    -   Vert. (hor.) FOV: θ_(v)(θ_(h))

In embodiments, a lookup table of P_(opt) to provide various displayluminance for various pupil size may be pre-computed and pre-provided todisplay power controller 114, using the above formulas, e.g., atmanufacturing time, at initial set up time, or during power oninitialization. In alternate embodiments, P_(opt) may be computed inreal time.

Continuing to refer to FIG. 1, in embodiments, wearable device 100 mayfurther include ambient light sensor 102 and pupil size calculator 110communicatively coupled with each other, and with display powercontroller 114 as shown. In embodiments, ambient light sensor 102 may beconfigured to sense and output ambient light level. In embodiments,similar to local light sensor 104, ambient light sensor 102 may be anyone of a number of suitable light sensors known in the art.

In embodiments, pupil size calculator 110 may be configured to estimatethe pupil size of the user, based at least in part on the sensed ambientlight level. In embodiments, pupil size calculator 110 may estimate theuser's pupil size, using a pupil size model 106 that models pupil sizesfor various ambient light levels.

In embodiments, pupil size model 106 may be represented by the followingformula:

$\begin{matrix}\begin{matrix}{{D_{U} = {{\frac{18.5172 + {0.122165\; f} - {0.105569\; y} + {0.000138645\; {fy}}}{2 + {0.0630635\; g}}\mspace{14mu} y} \geq 20}}\mspace{14mu}} \\{\mspace{670mu} (27)}\end{matrix} & (6) \\{{{with}\mspace{14mu} f} = {F^{0.41} = \left\lbrack {{LaM}(e)} \right\rbrack^{0.41}}} & \;\end{matrix}$

-   -   where D_(u) is the diameter of the pupil size, F is the        effective corneal flux density, and f is F elevated to the power        of 0.41.

$\left\{ {\begin{matrix}{{Ambient}\mspace{14mu} {luminance}\text{:}\mspace{14mu} {L\left( {c\; d\text{/}m^{2}} \right)}} \\{{Field}\mspace{14mu} {area}\text{:}\mspace{14mu} a\mspace{14mu} \left( \deg^{2} \right)} \\{{{{Monocular}\mspace{14mu} {effect}\text{:}\mspace{14mu} {M(1)}} = 0.1},{{M(2)} = 1}} \\{{Age}\text{:}\mspace{14mu} y\mspace{11mu} ({years})}\end{matrix}\quad} \right.$

Ambient luminance L is the parameter detected by ambient light sensors102. The field area is the user's FOV (field of view), in squaredegrees. A typical value may be between 60° ˜2700 square degrees.Monocular effect means either one eye, or two eyes. The age of the usermay be provided by the user. In embodiments, a reference or defaultedvalue, e.g., 30 years old, may be used instead. The result (D_(u)), isthe corresponding user pupil size in mm. See A unified formula forlight-adapted pupil size by Watson and Yellott, Journal of Vision(2012), 12(10); 12, 1-16 for further information.

In alternate embodiments, other pupil size models may be used.

Referring now to FIG. 2, wherein the retinal see through display powerdetermination technology of the present disclosure, according to variousother embodiments, is illustrated. Similar to wearable device 100,wearable device 200 may include retinal see through display (not shownin FIG. 2, see e.g., 406 in FIG. 4) having an exit pupil smaller thanactual eye pupil size or within possible eye pupil size range (2-7 mm).Further, like wearable device 100, wearable device 200 may includedisplay power controller 114, local light sensors 104 and target lightcalculator 112. Display power controller 114, local light sensors 104and target light calculator 112 may be similarly constituted and performthe same functions, as earlier described.

However, unlike wearable device 100, wearable device 200 include pupilsize detector 202, in lieu of ambient light sensor 102 and pupil sizecalculator 110. Pupil size detector 202 may be configured to detect(measure) the user's pupil size directly. Pupil size detector 202 may beany one of a number of suitable detectors known in the art.

Referring now to FIG. 4, wherein a component view of a wearable devicehaving the retinal see through display power determination technology ofthe present disclosure, according to various embodiments, isillustrated. As shown, wearable device 400 may include wearable body 410hosting hardware 401, i.e., hardware 401 are disposed on or withinwearable body 410. Hardware 401 in turn may host software 403. Inembodiments, hardware 401 may include one or more processors 402, memory404, retinal optical display 406, sensors 407 and other I/O devices 408.Software 403 may include operating system (OS) 412 and application 414.In embodiments, the wearable body 410 may be a pair of eyeglasses orgoggles.

Processor(s) 402 may be any one of a number of processors known in theart, having one or more processor cores. Memory 404 may be any volatileor non-volatile memory known in the art, suitable for storinginstructions and/or data, e.g., instructions and/or data of OS 412and/or applications 414. Except for its power being optimallycontrolled, retinal optical display 406 may otherwise be any one of anumber of retinal optical display known in the art. Sensors 407 may besensors 102 and 104 and/or pupil size detector 202 of FIGS. 1 and 2. Asdescribed earlier, they may be any one of a number of known sensorssuitable for sensing ambient and local lights, and/or detecting pupilsize of a user. Other I/O devices 408 may include e.g., but are notlimited to, Global Positioning System (GPS), gyroscope, accelerometer,compass, or communication or networking interfaces, such as WiFi, 3G/4G,Bluetooth®, Near Field Communication, Universal Serial Bus (USB) and soforth.

OS 412 may include a number of services and utilities 420, inparticular, optical display driver 422, incorporated with the teachingsof the present disclosure, e.g., pupil size calculator 110, target lightcalculator 112 and display power controller 114 of FIGS. 1 and 2. Exceptfor optical display driver 422, OS 112 may be any one of a number of OSknown in the art, e.g., the Windows OS from Microsoft® Corporation.Applications 114 may likewise be any one of a number of applicationsknown in the art.

Referring now to FIG. 5, wherein a process for determining optimal powerfor a retinal see through optical display, according to variousembodiments, is illustrated. As shown, process 500 for determiningoptimal power for a retinal see through optical display may includeoperations performed at blocks 502-512. The operations may be performede.g., by the earlier described optical device driver 422 of FIG. 4(having pupil size calculator 110, target light calculator 112 an/ordisplay power controller 114). Accordingly, FIG. 5 also depicts thealgorithmic structure of optical device driver 422 and its components.

As shown, process 500 may start at block 502, 506 or 508. At block 502,sensed ambient light data may be received. At bock 506, detected pupilsize of a user may be received. At block 510, sense local light data 510may be received.

From block 502, process 500 may proceed to block 504. At block 504, thepupil size of the user may be calculated/estimated. The pupil size ofthe user may be calculated/estimated using a pupil size model thatmodels pupil sizes for various ambient light conditions. As describedearlier, in some embodiments, the pupil size model may be represented bythe earlier described equation (6).

From block 508, process 500 may proceed to block 510. At block 510, therequired luminance level may be calculated/estimated. The requiredluminance level may be calculated/estimated using a required luminancemodel that models required luminance level for various local luminancelevels. As described earlier, in some embodiments, the requiredluminance model may be represented by the earlier described equation(1).

From block 504 or 506, and from block 510, process 500 may proceed toblock 512. At block 512, the optimal power of retinal see throughdisplay may be determined. In embodiments, the optimal power may be thepower that provides a display luminance level that approximates/equalsthe required luminance level for the user's pupil size. As describedearlier, the determination may be performed by retrieving the optimalpower from a lookup table pre-calculated in accordance with equations 5.In alternate embodiments, the calculations may be performed in real time(e.g., by a photodiode embedded in one of sensors 407 in FIG. 4).

As will be appreciated by one skilled in the art, aspects of the presentdisclosure may be embodied as methods or computer program products.Accordingly, aspects of the present disclosure, in addition to beingembodied in hardware as earlier described, may take the form of anentirely software embodiment (including firmware, resident software,micro-code, etc.) or an embodiment combining software and hardwareaspects that may all generally be referred to as a “circuit,” “module”or “system.” Furthermore, aspects of the present disclosure may take theform of a computer program product embodied in any tangible ornon-transitory medium of expression having computer-usable program codeembodied in the medium.

FIG. 6 illustrates an example computer-readable non-transitory storagemedium that may be suitable for use to store instructions that cause anapparatus, in response to execution of the instructions by theapparatus, to practice selected aspects of the present disclosure. Asshown, non-transitory computer-readable storage medium 602 may include anumber of programming instructions 604. Programming instructions 604 maybe configured to enable a wearable device, e.g., wearable device 500, inresponse to execution of the programming instructions, to implement(aspects of) OS 412, such as optical display driver 422. In alternateembodiments, programming instructions 604 may be disposed on multiplecomputer-readable non-transitory storage media 602 instead. In stillother embodiments, programming instructions 604 may be disposed oncomputer-readable transitory storage media 602, such as, signals.

Any combination of one or more computer usable or computer readablemedium(s) may be utilized. The computer-usable or computer-readablemedium may be, for example but not limited to, an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor system, apparatus,device, or propagation medium. More specific examples (a non-exhaustivelist) of the computer-readable medium would include the following: anelectrical connection having one or more wires, a portable computerdiskette, a hard disk, a random access memory (RAM), a read-only memory(ROM), an erasable programmable read-only memory (EPROM or Flashmemory), an optical fiber, a portable compact disc read-only memory(CD-ROM), an optical storage device, a transmission media such as thosesupporting the Internet or an intranet, or a magnetic storage device.Note that the computer-usable or computer-readable medium could even bepaper or another suitable medium upon which the program is printed, asthe program can be electronically captured, via, for instance, opticalscanning of the paper or other medium, then compiled, interpreted, orotherwise processed in a suitable manner, if necessary, and then storedin a computer memory. In the context of this document, a computer-usableor computer-readable medium may be any medium that can contain, store,communicate, propagate, or transport the program for use by or inconnection with the instruction execution system, apparatus, or device.The computer-usable medium may include a propagated data signal with thecomputer-usable program code embodied therewith, either in baseband oras part of a carrier wave. The computer usable program code may betransmitted using any appropriate medium, including but not limited towireless, wireline, optical fiber cable, RF, etc.

Computer program code for carrying out operations of the presentdisclosure may be written in any combination of one or more programminglanguages, including an object oriented programming language such asJava, Smalltalk, C++ or the like and conventional procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The program code may execute entirely on the user's wearabledevice, partly on the user's wearable device, as a stand-alone softwarepackage, partly on the user's wearable device and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's wearabledevice through any type of network, including a local area network (LAN)or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider).

The present disclosure is described with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the disclosure. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present disclosure. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an” and “the” are intended toinclude plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specific thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operation, elements,components, and/or groups thereof.

The corresponding structures, material, acts, and equivalents of allmeans or steps plus function elements in the claims below are intendedto include any structure, material or act for performing the function incombination with other claimed elements are specifically claimed. Thedescription of the present disclosure has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the disclosure in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill without departingfrom the scope and spirit of the disclosure. The embodiment was chosenand described in order to best explain the principles of the disclosureand the practical application, and to enable others of ordinary skill inthe art to understand the disclosure for embodiments with variousmodifications as are suited to the particular use contemplated.

Referring back to FIG. 4, for one embodiment, at least one of processors402 may be packaged together with memory having aspects of opticaldisplay driver 422. For one embodiment, at least one of processors 402may be packaged together with memory having aspects of optical displaydriver 422, to form a System in Package (SiP). For one embodiment, atleast one of processors 402 may be integrated on the same die withmemory having aspects of optical display driver 422. For one embodiment,at least one of processors 402 may be packaged together with memoryhaving aspects of optical display driver 422, to form a System on Chip(SoC). Thus various example embodiments of the present disclosure havebeen described including, but are not limited to:

Example 1 may be an apparatus for displaying images, comprising: a bodywearable by a user; a retinal see through display disposed in the body;a target light calculator disposed in the body to determine a requiredluminance level; and a display power controller communicatively coupledwith the target light calculator and the retinal see through display,and disposed in the body, to determine a power level for the retinal seethrough display to display images, based at least in part on a pupilsize of the user and the determined required luminance level.

Example 2 may be example 1, further comprising one or more ambient lightsensors disposed in the body to sense ambient light and output sensedambient light data, and a pupil size calculator coupled to the one ormore ambient light sensors, and disposed in the body, to estimate thepupil size of the user; wherein the pupil size calculator may estimatethe pupil size based at least in part on the sensed ambient light data.

Example 3 may be example 2, wherein the pupil size calculator mayestimate the pupil size based at least in part on the sensed ambientlight data, using a pupil size model that models pupil sizes for variousambient light conditions.

Example 4 may be example 1, further comprising a pupil size detectordisposed in the body to detect and output the pupil size of the user.

Example 5 may be example 1, further comprising one or more local lightsensors disposed in the body to sense local light and output sensedlocal light data associated with a local area behind a displayed virtualimage; wherein the target light calculator may determine the requiredluminance level, based at least in part on the sensed local light dataassociated with the local area behind the displayed virtual image.

Example 6 may be example 5, wherein the target light calculator maydetermine the required luminance level, based at least in part on thesensed local light data, using a required light model that modelsrequired light for various local light conditions.

Example 7 may be any one of examples 1-6; wherein the display powercontroller may determine the power level of the retinal see throughdisplay, such that a display luminance level approximates the determinedrequired luminance level, for the pupil size of the user.

Example 8 may be example 7, further comprising a processor disposed inthe body, wherein the target light calculator may be a software targetlight calculator operated by the processor, and the display powercontroller may be a software display power controller operated by theprocessor.

Example 9 may be example 8, wherein the target light calculator and thedisplay power controller may be part of an optical display driver.

Example 10 may be example 7, wherein the display power controllerincludes or may have access to a lookup table of pre-calculated powersto provide various display luminance levels for various pupil sizes.

Example 11 may be a method for displaying images, comprising:determining, by a wearable device, a required luminance level; anddetermining, by the wearable device, a power level of a retinal seethrough display of the wearable device to display images, based at leastin part on a pupil size of a user and the determined required luminancelevel.

Example 12 may be example 11, further comprising sensing ambient lightand outputting sensed ambient light data with one or more ambient lightsensors disposed in a body of the wearable device, and estimating thepupil size of the user, based at least in part on the sensed ambientlight data.

Example 13 may be example 12, wherein estimating may comprise estimatingthe pupil size based at least in part on the sensed ambient light data,using a pupil size model that models pupil sizes for various ambientlight conditions.

Example 14 may be example 11, further comprising detecting andoutputting the pupil size of the user using a pupil size detectordisposed in a body of the wearable device.

Example 15 may be example 11, further comprising sensing local light andoutputting sensed local light data associated with a local area behind adisplayed virtual image, using one or more local light sensors disposedin a body of the wearable device; wherein determining a requiredluminance level may comprise determining the required luminance level,based at least in part on the sensed local light data associated withthe local area behind the displayed virtual image.

Example 16 may be example 15, wherein determining the required luminancelevel may comprise determining the required luminance level, based atleast in part on the sensed local light data, using a required lightmodel that models required light for various local light conditions.

Example 17 may be any one of examples 11-16; wherein determining a powerlevel may comprise determining a power level of the retinal see throughdisplay, such that a display luminance level approximates the determinedrequired luminance level, for the pupil size of the user.

Example 18 may be example 17, wherein determining a power level maycomprise accessing a lookup table of pre-calculated powers to providevarious display luminance levels for various pupil sizes, to retrievethe power level.

Example 19 may be one or more computer-readable media comprisinginstructions that cause a wearable device, in response to execution ofthe instructions by the wearable device, to: determine a requiredluminance level; and determine a power level of a retinal see throughdisplay of the wearable device to display images, based at least in parton a pupil size of a user and the determined required luminance level.

Example 20 may be example 19, wherein the wearable device may compriseone or more ambient light sensors disposed in a body of the wearabledevice to sense ambient light and output sensed ambient light data; andwherein the wearable device may be further caused to estimate the pupilsize of the user, based at least in part on the sensed ambient lightdata.

Example 21 may be example 20, wherein the wearable device may be furthercaused to estimate the pupil size based at least in part on the sensedambient light data, using a pupil size model that models pupil sizes forvarious ambient light conditions.

Example 22 may be example 19, wherein the wearable device may comprise apupil size detector disposed in a body of the wearable device to detectand output the pupil size of the user.

Example 23 may be example 19, wherein the wearable device may compriseone or more local light sensors disposed in the body to sense locallight and output sensed local light data associated with a local areabehind a displayed virtual image; wherein the wearable device may befurther caused to determine the required luminance level, based at leastin part on the sensed local light data associated with the local areabehind the displayed virtual image.

Example 24 may be example 23, wherein the wearable device may be furthercaused to determine the required luminance level, based at least in parton the sensed local light data, using a required light model that modelsrequired light for various local light conditions.

Example 25 may be any one of examples 19-24; wherein the wearable devicemay be further caused to determine the power level of the retinal seethrough display, such that a display luminance level approximates thedetermined required luminance level, for the pupil size of the user.

Example 26 may be example 25, further comprising a lookup table ofpre-calculated powers to provide various display luminance levels forvarious pupil sizes.

Example 27 may be an apparatus for displaying images, comprising: meansfor determining a required luminance level; and means for determining apower level of a retinal see through display of the apparatus, based atleast in part on a pupil size of a user and the determined requiredluminance level.

Example 28 may be example 27, further comprising means for sensingambient light and outputting sensed ambient light data with one or moreambient light sensors disposed in a body of the wearable device, andmeans for estimating the pupil size of the user, based at least in parton the sensed ambient light data.

Example 29 may be example 28, wherein means for estimating may comprisemeans for estimating the pupil size based at least in part on the sensedambient light data, using a pupil size model that models pupil sizes forvarious ambient light conditions.

Example 30 may be example 27, further comprising means for detecting andoutputting the pupil size of the user using a pupil size detectordisposed in a body of the wearable device.

Example 31 may be example 27, further comprising means for sensing locallight and outputting sensed local light data associated with a localarea behind a displayed virtual image, using one or more local lightsensors disposed in a body of the wearable device; wherein means fordetermining a required luminance level may comprise means fordetermining the required luminance level, based at least in part on thesensed local light data associated with the local area behind thedisplayed virtual image.

Example 32 may be example 31, wherein means for determining the requiredluminance level may comprise means for determining the requiredluminance level, based at least in part on the sensed local light data,using a required light model that models required light for variouslocal light conditions.

Example 33 may be any one of examples 27-32; wherein means fordetermining a power level may comprise means for determining a powerlevel of the retinal see through display, such that a display luminancelevel approximates the determined required luminance level, for thepupil size of the user.

Example 34 may be example 33, wherein means for determining a powerlevel may comprise means for accessing a lookup table of pre-calculatedpowers to provide various display luminance levels for various pupilsizes, to retrieve the power level.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the disclosed embodiments ofthe disclosed device and associated methods without departing from thespirit or scope of the disclosure. Thus, it is intended that the presentdisclosure covers the modifications and variations of the embodimentsdisclosed above provided that the modifications and variations comewithin the scope of any claims and their equivalents.

What is claimed is:
 1. An apparatus for displaying images, comprising: abody wearable by a user; a retinal see through display disposed in thebody; a target light calculator disposed in the body to determine arequired luminance level; and a display power controller communicativelycoupled with the target light calculator and the retinal see throughdisplay, and disposed in the body, to determine a power level for theretinal see through display to display images, based at least in part ona pupil size of the user and the determined required luminance level. 2.The apparatus of claim 1, further comprising one or more ambient lightsensors disposed in the body to sense ambient light and output sensedambient light data, and a pupil size calculator coupled to the one ormore ambient light sensors, and disposed in the body, to estimate thepupil size of the user; wherein the pupil size calculator is to estimatethe pupil size based at least in part on the sensed ambient light data.3. The apparatus of claim 2, wherein the pupil size calculator is toestimate the pupil size based at least in part on the sensed ambientlight data, using a pupil size model that models pupil sizes for variousambient light conditions.
 4. The apparatus of claim 1, furthercomprising a pupil size detector disposed in the body to detect andoutput the pupil size of the user.
 5. The apparatus of claim 1, furthercomprising one or more local light sensors disposed in the body to senselocal light and output sensed local light data associated with a localarea behind a displayed virtual image; wherein the target lightcalculator is to determine the required luminance level, based at leastin part on the sensed local light data associated with the local areabehind the displayed virtual image.
 6. The apparatus of claim 5, whereinthe target light calculator is to determine the required luminancelevel, based at least in part on the sensed local light data, using arequired light model that models required light for various local lightconditions.
 7. The apparatus of claim 1; wherein the display powercontroller is to determine the power level of the retinal see throughdisplay, such that a display luminance level approximates the determinedrequired luminance level, for the pupil size of the user.
 8. Theapparatus of claim 7, further comprising a processor disposed in thebody, wherein the target light calculator is a software target lightcalculator operated by the processor, and the display power controlleris a software display power controller operated by the processor.
 9. Theapparatus of claim 8, wherein the target light calculator and thedisplay power controller are part of an optical display driver.
 10. Theapparatus of claim 7, wherein the display power controller includes orhas access to a lookup table of pre-calculated powers to provide variousdisplay luminance levels for various pupil sizes.
 11. A method fordisplaying images, comprising: determining, by a wearable device, arequired luminance level; and determining, by the wearable device, apower level of a retinal see through display of the wearable device todisplay images, based at least in part on a pupil size of a user and thedetermined required luminance level.
 12. The method of claim 11, furthercomprising sensing ambient light and outputting sensed ambient lightdata with one or more ambient light sensors disposed in a body of thewearable device, and estimating the pupil size of the user, based atleast in part on the sensed ambient light data.
 13. The method of claim12, wherein estimating comprises estimating the pupil size based atleast in part on the sensed ambient light data, using a pupil size modelthat models pupil sizes for various ambient light conditions.
 14. Themethod of claim 11, further comprising detecting and outputting thepupil size of the user using a pupil size detector disposed in a body ofthe wearable device.
 15. The method of claim 11, further comprisingsensing local light and outputting sensed local light data associatedwith a local area behind a displayed virtual image, using one or morelocal light sensors disposed in a body of the wearable device; whereindetermining a required luminance level comprises determining therequired luminance level, based at least in part on the sensed locallight data associated with the local area behind the displayed virtualimage.
 16. The method of claim 15, wherein determining the requiredluminance level comprises determining the required luminance level,based at least in part on the sensed local light data, using a requiredlight model that models required light for various local lightconditions.
 17. The method of claim 11; wherein determining a powerlevel comprises determining a power level of the retinal see throughdisplay, such that a display luminance level approximates the determinedrequired luminance level, for the pupil size of the user.
 18. The methodof claim 17, wherein determining a power level comprises accessing alookup table of pre-calculated powers to provide various displayluminance levels for various pupil sizes, to retrieve the power level.19. One or more computer-readable media comprising instructions thatcause a wearable device, in response to execution of the instructions bythe wearable device, to: determine a required luminance level; anddetermine a power level of a retinal see through display of the wearabledevice to display images, based at least in part on a pupil size of auser and the determined required luminance level.
 20. The one or morecomputer-readable media of claim 19, wherein the wearable devicecomprises one or more ambient light sensors disposed in a body of thewearable device to sense ambient light and output sensed ambient lightdata; and wherein the wearable device is further caused to estimate thepupil size of the user, based at least in part on the sensed ambientlight data.
 21. The one or more computer-readable media of claim 20,wherein the wearable device is further caused to estimate the pupil sizebased at least in part on the sensed ambient light data, using a pupilsize model that models pupil sizes for various ambient light conditions.22. The one or more computer-readable media of claim 19, wherein thewearable device comprises a pupil size detector disposed in a body ofthe wearable device to detect and output the pupil size of the user. 23.The one or more computer-readable media of claim 19, wherein thewearable device comprises one or more local light sensors disposed inthe body to sense local light and output sensed local light dataassociated with a local area behind a displayed virtual image; whereinthe wearable device is further caused to determine the requiredluminance level, based at least in part on the sensed local light dataassociated with the local area behind the displayed virtual image. 24.The one or more computer-readable media of claim 23, wherein thewearable device is further caused to determine the required luminancelevel, based at least in part on the sensed local light data, using arequired light model that models required light for various local lightconditions.
 25. The one or more computer-readable media of claim 19;wherein the wearable device is further caused to determine the powerlevel of the retinal see through display, such that a display luminancelevel approximates the determined required luminance level, for thepupil size of the user.